Zeitronix all the way.
I've got one and I love it.
The Zeitronix kit is cheaper than a prebuilt TechEdge kit (like $200 cheaper) and also has everything you'll need. The basic Z-kit does not have a LED readout, but supports data-logging, which is what you really want to utilize for tuning anyways and the unit it VERY small. Smaller than a deck of cards, so you can stash it just about anywhere. The TechEdge controller, on the other hand, is much bigger and needs a dedicated space to mount it. The Zeitronix also comes with the data-logging software (freeware) and is pretty good.
Definitely get the Zeitronix, especially if your money doesn't grow on trees.
-ic